The basic principles of induction heating have been known for quite some time. It has heretofore been known to utilize power sources including rectifiers and inverters in order to drive an induction heating coil, thereby producing an alternating magnetic field which is coupled through a planar cooking surface to a cooking pan in order to provide cooking action. Examples of such previously developed induction cooking systems may be found in U.S. Pat. No. 3,637,970 issued to Cunningham on Jan. 25, 1972 and entitled "Induction Heating Apparatus"; U.S. Pat. No. 3,697,716 issued to Kornrumpf on Oct. 10, 1972 and entitled "Induction Cooking Power Converter with Improved Coil Position" and U.S. Pat. No. 3,823,297 issued to Cunningham on July 9, 1974 and entitled "Load Controlled Induction Heating". It has also been known to utilize touch control devices to control the operation of such induction cooking devices.
Previously developed prior art induction cook-top devices have utilized induction heating coils which were directly interconnected to a supply voltage. This voltage was present at the induction heating coils even when the induction cook-top device was off. As a result, if the cook-top surface was damaged, thereby exposing the induction heating coil to the operator, a shock hazard was present. Therefore a need has arisen for an induction cook-top system that eliminates the occurrence of an electrical hazard should the cook-top surface be damaged.
The above-noted U.S. Pat. No. 4,169,222, and U.S. Pat. No. 4,149,217 describe an induction cook-top system and control panel including a bar graph display for displaying desired heating levels. Such a system, however, does not provide a centralized display of heating levels and includes costly electronic circuitry. Consequently, a need has arisen for an induction cook-top system which is economical to manufacture and simple in operation, including the use of a centralized display for conveniently and accurately displaying desired heating levels.